1. Field of the Invention
The present invention relates to an optical module interfacing device for connecting an UTP cable connector and an SFP type optical module to an SFP type optical module connector installed on a host board without additionally processing the UTP cable connector and the SFP type optical module, and an Ethernet system using the optical module interfacing device.
2. Description of the Related Art
As the Internet has rapidly come into wide use, Ethernet-based Internet networks require higher-speed and mass-storage capabilities, thus increasing capacity and the number of ports in an interfacing device of a system.
For example, in case that a single interfacing device processes traffic of 10 Gigabit capacity, the interfacing device requires at least ten Gigabit Ethernet ports.
According to definitions of IEEE 802.3z (1000 Base-X) and IEEE 802.3ab (1000 Base-T) standards, Gigabit Ethernet supports both an optical cable and a category 5 UTP cable. An interfacing device employing such Gigabit Ethernet ports selectively comprises an optical module based on the IEEE 802.3z standard or an RJ-45 port based on the IEEE 802.3ab standard.
A lower hierarchical structure of such a Gigabit Ethernet system will be described with reference to FIG. 1. As shown in FIG. 1, a register jack interface unit (hereinafter, referred to as an “RJ interface”) 103 or an optical module unit 104 is connected to a physical layer 102. Herein, the physical layer 102 is a Gigabit transceiver, which independently receives the RJ interface 103 and the optical module unit 104 so that users select the RJ interface 103 or the optical module unit 104 as occasion demands. The RJ interface 103 is a single line jack, such as an RJ-45 interface for digital transmission through a telephone cable (for example, a category 5 Unshielded Twisted Pair (hereinafter, referred to as a “UTP”) cable), and the optical module unit 104 is a means for converting an optical signal into an electric signal or an electric signal into an optical signal for digital transmission through an optical cable.
Here, a GMII (Gigabit Media Independent Interface) for connecting a media access control unit 101 and the physical layer 102 is an extended type of an MII (Media Independent Interface), and is a standard interface for supporting conventional 10 Mbps, 100 Mbps and 1,000 Mbps half-duplex and full-duplex communication systems.
The above RJ interface 103 serves as a connector installed on a LAN card of a conventional PC, and as shown in FIG. 2a, includes a female connector 211 installed on a host board 204 and a male connector 212 provided at an end of an UTP cable 213. 8 pins are formed at a corresponding position of each of the female connector 211 and the male connector 212.
The optical module 104 is the means for converting an optical signal into an electric signal or an electric signal into an optical signal, and is one selected from the group consisting of an SFF (Small Form Factor) type, an SFP (Small Form factor Pluggable) type, a GBIC (Gigabit Interface Conversion) type and a 1×9 transceiver type, according to shapes of packages employing the optical module 104. Since an SFF or SFP type optical module has a size half of that of a GBIC or 1×9 transceiver type optical module, the SFF or SFP type optical module is suitable for a system provided with several tens of optical modules.
Particularly, an SFP type optical module is a kind of a GBIC type optical module. As shown in FIG. 2b, the SFP type optical module 221 is designed such that an SFP connector 223 is installed at a designated position of a board 224, and a guide and an EMI shielding case 222 are covered on the SFP connector 223 so that the SFP optical module 221 is inserted into the EMI shielding case 222 and connected to the SFP connector 223. The SFP type optical module 221 is detachably mounted on the board 224, if necessary, thus being frequently and conveniently used. Here, the SFP type optical module 221 meets the requirements of the case 222, an electrical connector, the lay-out of the board 224 and an electrical interface based on MSA (Multi Source Agreement).
As described above, in case that an Ethernet system of 10 Gigabit or more receives both an optical cable and an UTP cable, each physical layer must independently include an optical module and an RJ interface, thus increasing the number of connectors provided on a host board and causing a limit in space on the host board.
Accordingly, in case that an interfacing device for receiving 10 Gigabit traffic is achieved in the Ethernet system and a user has the right of selection, the interfacing device requires at least 10 connectors for respectively connecting the optical modules and the RJ interfaces. Further, since one port corresponds to one of the optical module and the RJ interface, the number of ports substantially used is half of the total number of the ports, thus causing waste in cost and space. Moreover, in case that a cable is simultaneously inserted into the optical module and the RJ interface, there occurs confusion in selection between the optical module and the RJ interface.